Silicone rubber composition, adhesive and preparation method and application thereof

Abstract

The invention discloses a silicone rubber composition, an adhesive and a preparation method and application thereof, and relates to the technical field of organic silicon materials. The silicone rubber composition comprises vinyl silicone oil, hydrogen-containing polysiloxane, a tackifier, a coupling agent, a catalyst and a filler. The tackifier in the silicone rubber composition contains a-C = N structure, the structure can be hydrolyzed to generate-NH2, amino of the special structure can inhibit addition reaction and play a role of an inhibitor, long-chain alkyl on the left side of-C = N can shield tertiary amino, complete poisoning of a catalyst is avoided, and when the tackifier is matched with a coupling agent for use, the viscosity of the silicone rubber composition is reduced. The catalyst failure can be avoided while the long-term storage stability is realized, and the bonding strength is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic silicon materials, and in particular to a silicone rubber composition, an adhesive, and a preparation method and application thereof. Background Art

[0002] One-component addition liquid adhesive refers to a type of silicon material whose ingredients exist in the form of a single component. There is no need to mix components A and B. It can be cross-linked and vulcanized by heating to a certain temperature. The main component is silicone rubber. Its vulcanization speed can be controlled according to the temperature, and it has a high degree of flexibility and controllability. Due to these excellent properties, one-component addition liquid adhesive has been widely used in the fields of electronic component sealing, pipeline sealing, construction, medical equipment, aerospace, photovoltaic modules and automobile manufacturing. Especially in the occasions where high requirements are placed on bonding strength, weather resistance and insulation, the advantages of one-component addition liquid adhesive are more obvious.

[0003] However, due to the poor storage stability of single-component addition adhesives, long-term storage at room temperature is prone to increase in viscosity and decrease in bonding performance. Therefore, low-temperature storage and transportation are often required, which places relatively high storage and transportation costs. In order to improve the storage stability of single-component addition adhesives, there are currently three main solutions: introducing low-activity catalysts, using platinum catalyst coating, or using expensive acetylene alcohol inhibitors. These methods have the disadvantages of complex preparation processes and high costs. At the same time, the addition of inhibitors may also cause metal catalyst poisoning and failure, affecting the curing of silicone rubber molecular chains, resulting in incomplete curing or sticky surfaces after curing and decreased bonding strength.

[0004] In addition, although the bonding properties of one-component addition-type liquid silicone rubber have been improved through various methods, the bonding strength on certain specific substrates (such as PMMA) is still not ideal, and its application range is limited. Summary of the invention

[0005] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, the purpose of the present invention is to provide a silicone rubber composition, which is added with a specific tackifier and has the effects of both a tackifier and an inhibitor, and can improve the storage stability and bonding strength of silicone rubber without causing catalyst poisoning.

[0006] A second aspect of the present invention is to provide an adhesive.

[0007] The third aspect of the present invention is to provide a method for preparing an adhesive.

[0008] A fourth aspect of the present invention is to provide an application of a silicone rubber composition or an adhesive.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] The first aspect of the present invention provides a silicone rubber composition, comprising vinyl silicone oil, hydrogen-containing polysiloxane, a tackifier, a coupling agent, a catalyst and a filler; the tackifier comprises a compound represented by the following formula (I):

[0011]

[0012] Wherein, R1, R2 and R3 are hydrocarbon groups with carbon atoms ≥ 1

[0013] The silicone rubber composition of the present invention contains a tackifier with a specific structure. The hydrolysis of -C=N in the tackifier will generate -NH2. The amino group with a special structure will inhibit the addition reaction and play the role of an inhibitor, while the long-chain hydrocarbon group on the left of -C=N will shield the tertiary amino group to avoid complete poisoning of the catalyst. The tackifier of the present invention is used in combination with a coupling agent to achieve long-term storage stability while avoiding catalyst failure and improving bonding strength.

[0014] Preferably, the silicone rubber composition does not contain any inhibitor.

[0015] Preferably, the components of the silicone rubber composition are vinyl silicone oil, hydrogen-containing polysiloxane, a tackifier, a coupling agent, a catalyst and a filler.

[0016] Preferably, in the formula (I), R1 is a C1-C2 hydrocarbon group; R2 is a C1-C2 hydrocarbon group; and R3 is a C3-C5 hydrocarbon group.

[0017] C1-C5 means that the number of carbon atoms is 1 to 5.

[0018] Preferably, the tackifier comprises a compound of the following formula (1) and / or formula (2):

[0019]

[0020] Preferably, the vinyl silicone oil includes silicone oil containing terminal vinyl groups and / or pendant vinyl groups.

[0021] Preferably, the viscosity of the vinyl silicone oil at 25° C. is 1000 to 100000 mPa·s.

[0022] More preferably, the viscosity of the vinyl silicone oil at 25° C. is 1000 to 6000 mPa·s.

[0023] Preferably, the mass content of vinyl in the vinyl silicone oil is 0.1-5%.

[0024] More preferably, the mass content of vinyl in the vinyl silicone oil is 0.1-1%.

[0025] More preferably, the mass content of vinyl in the vinyl silicone oil is 0.1-0.5%.

[0026] Specifically, the mass content of vinyl in the vinyl silicone oil may be 0.1%, 0.2%, 0.3%, 0.4% or 0.5%.

[0027] Preferably, the hydrogen-containing polysiloxane includes at least one of terminal hydrogen-containing polysiloxane, side hydrogen-containing polysiloxane and terminal-side hydrogen-containing polysiloxane.

[0028] Preferably, the viscosity of the hydrogen-containing polysiloxane at 25° C. is 1 to 500 mPa·s.

[0029] More preferably, the viscosity of the hydrogen-containing polysiloxane at 25° C. is 10 to 150 mPa·s.

[0030] More preferably, the viscosity of the hydrogen-containing polysiloxane at 25° C. is 50 to 100 mPa·s.

[0031] Preferably, the hydrogen content of the hydrogen-containing polysiloxane is 0.01 to 1.6% by mass.

[0032] More preferably, the hydrogen mass content of the hydrogen-containing polysiloxane is 0.05 to 1%.

[0033] More preferably, the hydrogen content of the hydrogen-containing polysiloxane is 0.06-0.8% by mass.

[0034] Specifically, the hydrogen mass content of the hydrogen-containing polysiloxane may be 0.07%, 0.1%, 0.2%, 0.3%, 0.6%, 0.7% or 0.8%.

[0035] Preferably, the molar ratio of the hydrogen content in the hydrogen-containing polysiloxane to the vinyl content in the vinyl silicone oil is (1-5):1.

[0036] More preferably, the molar ratio of the hydrogen content in the hydrogen-containing polysiloxane to the vinyl content in the vinyl silicone oil is (2-4):1.

[0037] Specifically, the molar ratio of the hydrogen content in the hydrogen-containing polysiloxane to the vinyl content in the vinyl silicone oil may be 1:1, 2:1, 2.5:1, 3:1, 4:1, 4.5:1 or 5:1.

[0038] Preferably, the coupling agent includes at least one of ethyl titanate, butyl titanate, isopropyl titanate, tetra-tert-butyl titanate, tetra-tert-pentyl titanate, and titanate chelate.

[0039] The coupling agent of the present invention is selected from titanate coupling agents, which can catalyze the aminosilane reaction and promote bonding.

[0040] Preferably, the filler includes at least one of silicon dioxide, silicon powder, aluminum oxide, aluminum hydroxide, carbon black and white carbon black.

[0041] Preferably, the catalyst comprises a platinum catalyst.

[0042] More preferably, the platinum content in the platinum catalyst is 500-5000 ppm.

[0043] More preferably, the platinum content in the platinum catalyst is 2000-4000 ppm.

[0044] Preferably, the composition comprises the following components in parts by mass: 100 parts of vinyl silicone oil, 0.1 to 20 parts of hydrogen-containing polysiloxane, 0.1 to 10 parts of tackifier, 0.1 to 10 parts of coupling agent, 0.01 to 5 parts of catalyst and 1 to 1000 parts of filler.

[0045] More preferably, the composition comprises the following components in parts by mass: 100 parts of vinyl silicone oil, 3 to 9 parts of hydrogen-containing polysiloxane, 1 to 2 parts of tackifier, 1 to 2 parts of coupling agent, 0.05 to 0.2 parts of catalyst and 10 to 20 parts of filler.

[0046] The second aspect of the present invention is to provide an adhesive comprising the silicone rubber composition according to the first aspect of the present invention.

[0047] Preferably, the adhesive is an adhesive for difficult-to-bond substrates, and the difficult-to-bond substrates include PMMA.

[0048] The third aspect of the present invention is to provide a method for preparing the adhesive described in the second aspect of the present invention, using the silicone rubber composition described in the first aspect of the present invention as a raw material, comprising the following steps:

[0049] The vinyl silicone oil and filler are heated and mixed, and then the remaining components are added and mixed to obtain the bonding glue.

[0050] Preferably, the heating temperature is 80-200°C.

[0051] More preferably, the heating temperature is 120-150°C.

[0052] Preferably, the preparation method comprises the following steps:

[0053] The vinyl silicone oil and filler are heated and mixed, and mixed for 1 to 3 hours under vacuum conditions to remove free moisture; then the remaining components are added and mixed for 30 to 90 minutes under vacuum to obtain the adhesive.

[0054] The fourth aspect of the present invention provides an application of the silicone rubber composition described in the first aspect of the present invention or the adhesive described in the second aspect of the present invention in the fields of electronic components, automobiles, home appliances, medical equipment or construction.

[0055] Preferably, the household appliances include electric kettles, induction cookers, microwave ovens, heaters, etc.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] (1) The silicone rubber composition of the present invention contains a tackifier of a specific structure, which contains an amino group in its structure, can inhibit the addition reaction, improve storage stability, and will not poison the platinum catalyst due to its special structure. The silicone rubber composition of the present invention uses a conventional platinum catalyst and does not require additional inhibitors to achieve the effect of not thickening when stored at room temperature for more than 6 months, thereby reducing production costs. At the same time, the use of a coupling agent can make the silicone rubber composition of the present invention have a wider bonding range and better adhesion.

[0058] (2) The silicone rubber composition of the present invention has excellent long-term storage stability and bonding strength, and will not cause catalyst poisoning. It can be used for adhesive glue, has a wide range of adhesion to various substrates, and can improve the bonding strength of difficult-to-bond substrates (such as PMMA).

[0059] (3) The adhesive of the present invention does not need to add an inhibitor, and uses a tackifier with a special structure. The catalyst does not need to undergo specific treatment and will not be poisoned. The preparation method is simple and the process is simple. No new equipment or process steps are required, and the production cost is low.

[0060] (4) The adhesive formed by the silicone rubber composition of the present invention is a one-component addition-type thermally conductive liquid adhesive, which not only has good stability and bonding performance, but also has the characteristics of low odor, environmental protection, and non-toxicity, meets food grade requirements, and can be used in electronic components, automobiles, home appliances, medical equipment or construction fields, especially in the bonding and sealing of electric kettles, induction cookers, microwave ovens, PTC ceramic heaters and other electric control boxes. DETAILED DESCRIPTION

[0061] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0062] Some of the raw materials of the following embodiments and comparative examples of the present invention are described as follows:

[0063] Vinyl silicone oil:

[0064] A1: vinyl-terminated polydimethylsiloxane; 25°C viscosity = 1000 mPa·s; vinyl content = 0.32 wt%;

[0065] A2: vinyl-terminated polydimethylsiloxane; viscosity at 25°C = 5000 mPa·s; vinyl content = 0.16 wt%; filler.

[0066] B: Hydrophobic fumed silica; specific surface area: 200m 2 / g.

[0067] Hydrogenated polysiloxane:

[0068] C1: Side hydrogenated silicone oil, 25℃ viscosity = 80mPa·s; hydrogen content = 0.75w%;

[0069] C2: Side hydrogenated silicone oil, 25°C viscosity = 100 mPa·s; hydrogen content = 0.29 wt%;

[0070] C3: hydrogen-terminated silicone oil, viscosity at 25°C = 50 mPa·s; hydrogen content = 0.07 wt%.

[0071] Tackifier:

[0072] D1: Prepared by Mannich reaction of aminopropyltrimethoxysilane and 4-methyl-2-pentanone under acidic conditions; D2: It is prepared by Mannich reaction of aminopropyltriethoxysilane and 4-methyl-2-pentanone under acidic conditions; D3: γ-aminopropyltriethoxysilane (KH-550).

[0073] Coupling agent:

[0074] E1: tetraisobutyl titanate;

[0075] E2: bis(ethyl acetoacetate) and bis(alkoxy)titanium.

[0076] catalyst:

[0077] F: bis(1,3-divinyl-1,1,3,3-tetramethyldisiloxane)platinum, platinum content of 3000 ppm.

[0078] The following is a detailed description with reference to the embodiments and comparative examples.

[0079] Example 1

[0080] This embodiment provides an adhesive consisting of a silicone rubber composition, and the specific formula is shown in Table 1.

[0081] The preparation method of the adhesive of this embodiment comprises the following steps:

[0082] 1) Add vinyl silicone oil to a kneader, then add fillers in batches, heat to 120°C, evacuate, stir for 3 hours, remove free moisture, and cool to room temperature as a base glue for standby use;

[0083] 2) Add the base glue into a planetary mixer, add hydrogen-containing polysiloxane, tackifier, coupling agent and catalyst, and stir under vacuum for 30 minutes to obtain an adhesive glue.

[0084] Embodiments 2 to 7

[0085] Examples 2 to 7 provide an adhesive, and the differences from Example 1 are shown in Table 1.

[0086] The preparation method of the adhesives of Examples 2 to 7 is the same as that of Example 1.

[0087] Comparative Examples 1 to 3

[0088] Comparative Examples 1 to 3 provide an adhesive, and the differences from Example 1 are shown in Table 1; the preparation method is the same as that of Example 1.

[0089] Table 1 Formulation of adhesives of Examples 1 to 7 and Comparative Examples 1 to 3 (parts by mass)

[0090]

[0091] Results

[0092] The performance of the adhesives obtained in the above embodiments and comparative examples was tested.

[0093] (1) Viscosity: The viscosity of the sample at room temperature is tested in accordance with GB / T2794-2022.

[0094] (2) Shear strength: The adhesive was applied on two substrate test pieces, and then the test pieces were bonded together, cured at 130°C for 60 min, and cured at room temperature for 24 h. The tensile shear strength of the samples was tested in accordance with GB / T 7124-2008.

[0095] The test results are shown in Tables 2 and 3 below.

[0096] Table 2 Adhesive properties test results of the embodiment

[0097]

[0098]

[0099] Table 3 Adhesive performance test results of comparative examples

[0100]

[0101] Comparing the data in Table 2 and Table 3, it can be seen that the adhesive of the present invention achieves long-term storage stability at room temperature without adding an inhibitor, can be stably stored for 180 days, and will not have the problem of viscosity doubling after being stored at room temperature for 360 days. The viscosity change in 180 days of storage is as low as 1.3%, and the viscosity change in 360 days is as low as 3.9%. At the same time, the adhesive prepared from the silicone rubber composition of the present invention also has excellent bonding performance, and its initial shear strength for aluminum substrate is not less than 2.35MPa, the shear strength for stainless steel substrate is not less than 2.3MPa, and the shear strength for PMMA (polymethyl methacrylate) substrate is not less than 1.75MPa, which is better than conventional adhesives for difficult-to-bond substrates such as PMMA.

[0102] Compared with Example 1, Comparative Example 1 does not add a tackifier. The adhesive gels after being stored at room temperature for 180 days, and the storage stability is poor, which indicates that the tackifier of the present invention has the effect of an inhibitor and can achieve improved long-term storage stability.

[0103] In Comparative Example 2, only a tackifier is added without a coupling agent, and the storage stability of the obtained adhesive is reduced, and the bonding strength is reduced. The bonding strength for the three substrates does not exceed 0.5 MPa.

[0104] Compared with Example 1, in Comparative Example 3, only γ-aminopropyltriethoxysilane is used as a thickener. Although its structure itself can provide amino groups, the compound structure is different from the thickener of the present invention. Although the amino groups in its structure have a certain inhibitory effect on the addition reaction, that is, avoiding excessive increase in viscosity, it will also cause platinum catalyst poisoning, and the obtained adhesive cannot be cured, and bonding cannot be achieved.

[0105] In summary, the adhesive formed by the silicone rubber composition of the present invention has good storage stability, and because the special structure of the tackifier will not poison the platinum catalyst, it is not necessary to add an additional inhibitor to achieve the effect of not thickening for more than 6 months of storage at room temperature, thereby reducing production costs. At the same time, the use of a tackifier with a coupling agent improves the bonding range, has good adhesion, and can improve the bonding strength of difficult-to-bond substrates (such as PMMA). In addition, the adhesive belongs to a one-component addition type liquid adhesive, and the preparation method is simple, the process is simple, no new equipment or process steps are required, and the production cost is low. It can be used in electronic components, automobiles, household appliances, medical equipment or construction fields, especially electric kettles, induction cookers, microwave ovens, PTC ceramic heaters and other electric control boxes. Adhesive seals.

[0106] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A silicone rubber composition, characterized in that: The invention comprises vinyl silicone oil, hydrogen-containing polysiloxane, a tackifier, a coupling agent, a catalyst and a filler; the tackifier comprises a compound represented by the following formula (I): Wherein, R1, R2 and R3 are all hydrocarbon groups with carbon number ≥1.

2. The silicone rubber composition according to claim 1, characterized in that The vinyl silicone oil includes silicone oil containing terminal vinyl groups and / or side vinyl groups; and / or, the viscosity of the vinyl silicone oil at 25° C. is 1000 to 100000 mPa·s; And / or, the mass content of vinyl in the vinyl silicone oil is 0.1-5%.

3. The silicone rubber composition according to claim 1, characterized in that: The hydrogen-containing polysiloxane includes at least one of terminal hydrogen-containing polysiloxane, side hydrogen-containing polysiloxane, and terminal-side hydrogen-containing polysiloxane; and / or, the viscosity of the hydrogen-containing polysiloxane at 25° C. is 1 to 500 mPa·s; And / or, the hydrogen content of the hydrogen-containing polysiloxane is 0.01 to 1.6% by mass.

4. The silicone rubber composition according to claim 2 or 3, characterized in that: The molar ratio of the hydrogen content in the hydrogen-containing polysiloxane to the vinyl content in the vinyl silicone oil is (1-5):

1.

5. The silicone rubber composition according to claim 1, characterized in that: The coupling agent includes at least one of ethyl titanate, butyl titanate, isopropyl titanate, tetra-tert-butyl titanate, tetra-tert-pentyl titanate, and titanate chelate; And / or, the filler includes at least one of silicon dioxide, silicon powder, aluminum oxide, aluminum hydroxide, carbon black, and white carbon black; And / or, the catalyst comprises a platinum catalyst.

6. The silicone rubber composition according to claim 1 or 5, characterized in that: The invention comprises the following components in parts by mass: 100 parts of vinyl silicone oil, 0.1 to 20 parts of hydrogen-containing polysiloxane, 0.1 to 10 parts of tackifier, 0.1 to 10 parts of coupling agent, 0.01 to 5 parts of catalyst and 1 to 1000 parts of filler.

7. An adhesive, characterized in that: The silicone rubber composition comprises the silicone rubber composition according to any one of claims 1 to 6.

8. A method for preparing the adhesive according to claim 7, characterized in that: Using the silicone rubber composition according to any one of claims 1 to 6 as a raw material, the method comprises the following steps: The vinyl silicone oil and filler are heated and mixed, and then the remaining components are added and mixed to obtain the bonding glue.

9. The preparation method according to claim 8, characterized in that: The heating temperature is 80-200°C.

10. Use of the silicone rubber composition according to any one of claims 1 to 6 or the adhesive according to claim 7 in the fields of electronic components, automobiles, home appliances, medical equipment or construction.

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